Large-screen, high-picture-quality display devices have received much attention recently. Various large-screen display devices have been developed and commercially available.
A projection display device, namely, a projector, is an example of such a large-screen display device. Generally, the projector projects an image produced in a display element onto a screen using the light emitted from a light source, and thereby displays the image. Recently, a projector having an ultra-mini size has been developed.
Such a projector is referred to as a “pico-projector”. This projector can be internally or externally equipped in a portable terminal such as a mobile phone, a notebook computer, or a portable multimedia player (PMP), or in a desktop computer.
The projector can include a virtual keyboard for projecting a virtual keyboard image onto a surface or floor, and for sensing a motion of the user s finger on the projected keyboard image, thereby recognizing a key input.